Re: [RFC/PATCH v1 1/3] v4l: Add new framesamples field to struct v4l2_mbus_framefmt

[Tomasz Stanislawski <t.stanislaws@samsung.com>]

Hi

On 11/22/2011 10:55 AM, Sylwester Nawrocki wrote:
> The purpose of the new field is to allow the video pipeline elements to
> negotiate memory buffer size for compressed data frames, where the buffer
> size cannot be derived from pixel width and height and the pixel code.
>
> For VIDIOC_SUBDEV_S_FMT and VIDIOC_SUBDEV_G_FMT ioctls, the framesamples
> parameter should be calculated by the driver from pixel width, height,
> color format and other parameters if required and returned to the caller.
> This applies to compressed data formats only.
>
> The application should propagate the framesamples value, whatever returned
> at the first sub-device within a data pipeline, i.e. at the pipeline's data
> source.
>
> For compressed data formats the host drivers should internally validate
> the framesamples parameter values before streaming is enabled, to make sure
> the memory buffer size requirements are satisfied along the pipeline.
>
> Signed-off-by: Sylwester Nawrocki<s.nawrocki@samsung.com>
> Signed-off-by: Kyungmin Park<kyungmin.park@samsung.com>
> ---
>   Documentation/DocBook/media/v4l/subdev-formats.xml |    7 ++++++-
>   include/linux/v4l2-mediabus.h                      |    4 +++-
>   2 files changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/DocBook/media/v4l/subdev-formats.xml b/Documentation/DocBook/media/v4l/subdev-formats.xml
> index 49c532e..d0827b4 100644
> --- a/Documentation/DocBook/media/v4l/subdev-formats.xml
> +++ b/Documentation/DocBook/media/v4l/subdev-formats.xml
> @@ -35,7 +35,12 @@
>   	</row>
>   	<row>
>   	<entry>__u32</entry>
> -	<entry><structfield>reserved</structfield>[7]</entry>
> +	<entry><structfield>framesamples</structfield></entry>

Why you do not use name sizeimage?
It is used in struct v4l2_plane_pix_format and struct v4l2_pix_format?

Should old drivers be modified to update this field?

Best regards,
Tomasz Stanislawski

> +	<entry>Number of data samples on media bus per frame.</entry>
> +	</row>
> +	<row>
> +	<entry>__u32</entry>
> +	<entry><structfield>reserved</structfield>[6]</entry>
>   	<entry>Reserved for future extensions. Applications and drivers must
>   	  set the array to zero.</entry>
>   	</row>
> diff --git a/include/linux/v4l2-mediabus.h b/include/linux/v4l2-mediabus.h
> index 5ea7f75..ce776e8 100644
> --- a/include/linux/v4l2-mediabus.h
> +++ b/include/linux/v4l2-mediabus.h
> @@ -101,6 +101,7 @@ enum v4l2_mbus_pixelcode {
>    * @code:	data format code (from enum v4l2_mbus_pixelcode)
>    * @field:	used interlacing type (from enum v4l2_field)
>    * @colorspace:	colorspace of the data (from enum v4l2_colorspace)
> + * @framesamples: number of data samples per frame
>    */
>   struct v4l2_mbus_framefmt {
>   	__u32			width;
> @@ -108,7 +109,8 @@ struct v4l2_mbus_framefmt {
>   	__u32			code;
>   	__u32			field;
>   	__u32			colorspace;
> -	__u32			reserved[7];
> +	__u32			framesamples;
> +	__u32			reserved[6];
>   };
>
>   #endif